Numerical simulation of methane explosion shock waves and flame propagation characteristics in multibranch pipelines

This study investigated the effects of sudden structural changes, such as bends, bifurcations, and parallel branches, on explosion overpressure and flame propagation characteristics. Gas explosion experiments were conducted using a typical multibranch pipeline experimental platform to reflect actual roadway dimensions. The findings were validated through numerical simulation. Results indicated that after gas explosion, the shockwave overpressure and flame propagated rapidly forward. The peak explosion overpressure reached 2.5 MPa, with high-temperature gases primarily continuing forward along the left and right conduits. The shockwave was reflected and superimposed at the angular junction, forming a localized overpressure of 1.8 MPa. As the propagation distance increased, overpressure diminished, and the flame gradually extinguished. Flame propagation was influenced by the multibranch pipeline structure and primarily proceeded along the parallel branches. The flame failed to enter the branch lines, and the maximum propagation velocity was 312.85 m/s within the parallel branches. Overpressure and flame propagation mutually reinforced and constrained each other. Shock wave overpressure generated vortex structures at abrupt structural transitions, prolonging the flame duration and altering the flame propagation paths. Concurrently, flame morphology influenced overpressure decay and exacerbated explosion hazards. These findings provide theoretical reference for research on prevention and control technologies for coal mine gas and coal dust explosions and for formulating postdisaster emergency response plans.